The present invention relates to glucose monitoring systems in general and, more particularly, to an improvement in the method and apparatus for controlling blood glucose concentrations in a subject by selected infusion of insulin.
Methods and apparatus for the analysis of blood glucose concentration and the infusion of insulin based upon such analysis are known in the prior art, as can be found in U.S. Pat. No. 4,151,845.
In systems such as the one aforementioned, the concentration of glucose in the bloodstream of a subject is controlled by infusion of insulin to the subject dependent upon the concentration of glucose in the subject's bloodstream. In such an apparatus, means are provided for determining the serial values of blood glucose concentration in the blood from minute-to-minute and for providing computer input signals corresponding to those serial values to an interface which in turn controls infusion means connected thereto and to a source of insulin. The infusion means is responsive to the output of the interface for introducing insulin from the source into the bloodstream at a rate determined thereby. The computer is programmed to provide, in response to its input signals, output signals which cause the infusion of insulin in accordance with an algorithm wherein there is a required basal infusion rate RI for the desired basal or steady state glucose concentration BI for that patient.
In such systems, the required basal infusion rate RI for a desired basal or steady state glucose concentration has been estimated for each subject and thereafter an operator used trial and error to achieve the correct value, however, until the correct value was reached, the apparatus was not able to achieve the desired basal steady state glucose concentration.